發(fā)布時間：2018-03-23 23:31

  本文選題：光子晶體光纖　切入點：圖像處理　出處：《天津工業(yè)大學》2017年碩士論文

【摘要】：隨著光子晶體光纖的發(fā)展和研究,擁有特殊結(jié)構(gòu)和靈活性特性的光子晶體光纖應(yīng)用越來越廣泛,精確測量光子晶體光纖的性能成為了研究重點。針對實際光子晶體光纖由于結(jié)構(gòu)不規(guī)則難以進行數(shù)值分析的缺點,本文基于圖像處理算法對光子晶體光纖掃描電鏡截面圖像進行處理,并在此基礎(chǔ)上提取出光纖的幾何結(jié)構(gòu)作為測量其特性的模型,然后在COMSOL Mutilphysics軟件上利用重建的幾何結(jié)構(gòu)模型結(jié)合光子晶體光纖的有限元數(shù)值分析方法對其色散數(shù)值模擬,提高了光子晶體光纖光學特性的評價準確真實性。本文的主要工作是利用圖像處理算法對光子晶體光纖進行幾何結(jié)構(gòu)重建,實現(xiàn)精確建模的關(guān)鍵是對光纖截面圖像的識別和精確提取。首先對PCF截面圖像采用中值濾波和閾值分割等圖像處理方法進行偽信息預(yù)處理,選用經(jīng)典Canny算子檢測尋找其邊緣,然后利用改進亞像素算法篩選出精確的邊緣信息,精確定位PCF截面圖像的結(jié)構(gòu)邊緣;其次利用基于RANSAC算法改進的最小二乘法對圖像的特征點進行擬合操作,即用隨機抽樣法對已提取的圖像特征點篩選,剔除幾何結(jié)構(gòu)模型中誤差較大的特征點后,再使用最小二乘法對篩選后的特征點進行擬合操作,對提取的幾何特征擬合出最優(yōu)幾何—橢圓;最后在基于霍夫曼變換的基礎(chǔ)上,引入了同心圓橢圓檢測算法,利用上述算法能夠?qū)孛娼Y(jié)構(gòu)進行很好的識別及提取,建立起最優(yōu)光纖模型。利用已經(jīng)得到了 PCF截面的重構(gòu)模型,在COMSOLMutilphysics軟件平臺上結(jié)合光子晶體光纖的有限元數(shù)值分析法進行色散數(shù)值模擬,并對計算結(jié)果進行誤差分析。用這種方法,本文重建了一種實際光子晶體光纖產(chǎn)品的掃描電鏡截面圖像的結(jié)構(gòu)和分析了其色散性質(zhì),數(shù)據(jù)計算結(jié)果符合產(chǎn)品參數(shù)。
[Abstract]:With the development and research of photonic crystal fiber, photonic crystal fiber with special structure and flexibility is more and more widely used. The accurate measurement of the performance of photonic crystal fiber has become the focus of research. In view of the disadvantage of practical photonic crystal fiber which is difficult to be numerically analyzed because of its irregular structure, In this paper, the scanning electron microscope cross-section image of photonic crystal fiber is processed based on image processing algorithm, and the geometrical structure of optical fiber is extracted as the model to measure its characteristics. Then the dispersion of photonic crystal fiber is simulated by using the reconstructed geometric structure model and the finite element numerical analysis method of photonic crystal fiber on COMSOL Mutilphysics software. The evaluation of optical properties of photonic crystal fiber is improved. The main work of this paper is to reconstruct the geometrical structure of photonic crystal fiber by image processing algorithm. The key to accurate modeling is to recognize and extract the cross-section image of optical fiber. Firstly, the image processing methods such as median filter and threshold segmentation are used to preprocess the pseudo-information, and the classical Canny operator is used to detect and find the edge of the image. Then the improved sub-pixel algorithm is used to filter out the accurate edge information and locate the structural edge of the PCF section image accurately. Secondly, the improved least square method based on the RANSAC algorithm is used to fit the feature points of the image. The method of random sampling is used to screen the feature points of the extracted images. After the feature points with large errors in the geometric structure model are eliminated, the least square method is used to fit the selected feature points. The optimal geometric ellipse is fitted to the extracted geometric features. Finally, based on the Huffman transform, a concentric circle ellipse detection algorithm is introduced, which can be used to identify and extract the cross-section structure. The optimal fiber model is established and the dispersion numerical simulation is carried out by using the reconstructed model of PCF cross section and the finite element numerical analysis of photonic crystal fiber on the platform of COMSOLMutilphysics. By using this method, the structure and dispersion properties of an actual photonic crystal fiber product section image of scanning electron microscope are reconstructed and analyzed. The calculated results are in accordance with the product parameters.
【學位授予單位】：天津工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O734;TP391.41

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本文編號：1655719